A generic testing framework for agent-based simulation models

International audienceAgent-based modelling and simulation (ABMS) had an increasing attention during the last decade. However, the weak validation and verification of agent-based simulation models makes ABMS hard to trust. There is no comprehensive tool set for verification and validation of agent-based simulation models, which demonstrates that inaccuracies exist and/or reveals the existing errors in the model. Moreover, on the practical side, many ABMS frameworks are in use. In this sense, we designed and developed a generic testing framework for agent-based simulation models to conduct validation and verification of models. This paper presents our testing framework in detail and demonstrates its effectiveness by showing its applicability on a realistic agent-based simulation case study

Mimicking human neuronal pathways in silico: an emergent model on the effective connectivity

International audienceWe present a novel computational model that detects temporal configurations of a given human neuronal pathway and constructs its artificial replication. This poses a great challenge since direct recordings from individual neurons are impossible in the human central nervous system and therefore the underlying neuronal pathway has to be considered as a black box. For tackling this challenge, we used a branch of complex systems modeling called artificial self-organization in which large sets of software entities interacting locally give rise to bottom-up collective behaviors. The result is an emergent model where each software entity represents an integrate-and-fire neuron. We then applied the model to the reflex responses of single motor units obtained from conscious human subjects. Experimental results show that the model recovers functionality of real human neuronal pathways by comparing it to appropriate surrogate data. What makes the model promising is the fact that, to the best of our knowledge, it is the first realistic model to self-wire an artificial neuronal network by efficiently combining neuroscience with artificial self-organization. Although there is no evidence yet of the model's connectivity mapping onto the human connectivity, we anticipate this model will help neuroscientists to learn much more about human neuronal networks, and could also be used for predicting hypotheses to lead future experiments

Cross-reactive CD4+ T cells enhance SARS-CoV-2 immune responses upon infection and vaccination

The functional relevance of pre-existing cross-immunity to SARS-CoV-2 is a subject of intense debate. Here, we show that human endemic coronavirus (HCoV)-reactive and SARS-CoV-2-cross-reactive CD4+ T cells are ubiquitous but decrease with age. We identified a universal immunodominant coronavirus-specific spike peptide (S816-830) and demonstrate that pre-existing spike- and S816-830-reactive T cells were recruited into immune responses to SARS-CoV-2 infection and their frequency correlated with anti-SARS-CoV-2-S1-IgG antibodies. Spike-cross-reactive T cells were also activated after primary BNT162b2 COVID-19 mRNA vaccination displaying kinetics similar to secondary immune responses. Our results highlight the functional contribution of pre-existing spike-cross-reactive T cells in SARS-CoV-2 infection and vaccination. Cross-reactive immunity may account for the unexpectedly rapid induction of immunity following primary SARS-CoV-2 immunization and the high rate of asymptomatic/mild COVID-19 disease courses

İzmir İli Alaçtı Beldesinde sörf sporu örneğinde, spor ve spor yerleri üzerine bir araştırma

Spor, günümüzde günlük hayatın bir parçası olmak zorunda olan fiziksel ve mental bir ihtiyaçtır. İnsanın özelliklerini güçlendiren, toplumu birleştiren, daha iyi bir dünya için umut veren bir konudur. Bu nedenlerden dolayı her zaman spor, önemsenmeli ve gereken önem verilmelidir. Rüzgar sörfü, bir su sporu ve aynı zamanda da doğa sporudur. Dört tarafı denizlerle çevrili ülkemizde rüzgar sörfü yapmak için koşul olarak uygun olan bir çok yer vardır. Ama bu yerler arasında koşullar bakımından dünyada da örnek olan bir yerimiz, Alaçatı’dır diyebiliriz. Ayrıca Alaçatı, rüzgar sörfü konusunda dünyada bilinen bir yer durumundadır. Dünyanın en büyük uluslararası rüzgar sörfü yarışmaları bu yüzden bu alanda organize edilebilmektedir. Binlerce kişi her yıl, sörf öğrenmekte, yarışmalara katılmakta ve bu nedenle rekreasyonel amaçlı olarak Alaçatı’ya gelmektedirler. Bu yüzden Alaçatı ilçesi Sörf koyu olarak, ayrıca hem deniz, hem karasal olarak kanunların dışında özel bir statüye sahip olmalı ve özellikle kıyı kenarı ve deniz üstünde sporu destekleyecek düzenlemeler yapılabilmeli ve ayrıca spora destek ve hizmet veren yatırımcılar ve işletmeler sporun ihtiyaçları doğrultusunda iyi bir şekilde yönlendirilmelidirler. Bu yönlendirmeler ve yapılacak kıyı düzenlemeleri sörf sporuna özel bir peyzaj planlama ve çevre düzenleme çerçevesinde gerçekleştirilmelidir

Wave-number spectrum of dissipative drift waves and a transition scale

International audienceWe study the steady state spectrum of the Hasegawa-Wakatani (HW) equations that describe drift wave turbulence. Beyond a critical scale kc, which appears as a balance between the nonlinear time and the parallel conduction time, the adiabatic electron response breaks down nonlinearly and an internal energy density spectrum of the form F(k⊥)∝k−3⊥, associated with the background gradient, is established. More generally a dual power law spectrum, approximately of the form F(k⊥)∝k−3⊥(k−2c k−2⊥) is obtained, which captures this transition. Using dimensional analysis, an expression of the form kc∝C/κ is derived for the transition scale, where C and κ are normalized parameters of the HW equations signifying the electron adiabaticity and the density gradient, respectively. The results are numerically confirmed using a shell model developed and used for the Hasegawa-Wakatani system

Mapping with WorldView-1 Imagery

With the new very high resolution optical satellites WorldView-1 and GeoEye-1 images with 0.5m ground sampling distance (GSD) are available. By the rule of thumb of required 0.1mm GSD in the presentation scale of a topographic data base, it should be possible to generate topographic maps up to the scale 1: 5000 with such satellite imagery. The orientation of WorldView-1 images is possible with sub-pixel accuracy - totally satisfying for topographic data acquisition. More difficult as before is the required accuracy of digital elevation models for the generation of ortho images if the data acquisition shall be done by on-screen digitizing of ortho images